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New Reasons to Change Light Bulbs

LED Light Bulbs: LED bulbs are a gigantic improvement over incandescent bulbs and compact fluorescents. David Pogue tries out LED bulbs and kits from six manufacturers.
http://www.nytimes.com/2013/03/21/technology/personaltech/cheaper-led-bulbs-make-it-easier-to-switch-lights.html?pagewanted=all


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Addressing Fears About LED Light Bulbs
March 21, 2013
http://pogue.blogs.nytimes.com/2013/03/21/addressing-fears-about-led-light-bulbs/ [with comments]


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FIPEL: more on the OLED-alternative light source

Tuesday 04 December 2012 15:24

US scientists have created a bright efficient area light source to compete with fluorescent tubes and OLEDs, it is claimed.

Developed at Wake Forest University of North Carolina, the field-induced polymer electroluminescent (FIPEL) is a planar light emitting structure energised by an AC field from insulated electrodes.

There is no junction. Instead the key component is a layer of polymer loaded with an iridium compound and doped multi-wall carbon nanotubes.

"The AC stimulates displacement current in the polymer, in which we have placed charge sources and field sinks from nano-materials," project head Professor David Carroll told Electronics Weekly. "The big concern for AC devices is loss in dielectric. Nano particles make it tremendously non-lossy."

The polymer mix has three different emission centres coupled with triplet scavengers, said Carroll: "You get singlets and triplets and the triplets are non-radiative. Normally OLEDs have scavengers too. In our's, the effectiveness of triplet to singlet conversion is far higher."

Its structure is similar to well-established AC electroluminescent technology.

"In AC electroluminescent, light output is around 0.1cd/A. OLED delivers 50cd/A, and ours is 62cd/A," claimed Carroll.

This 62cd/A figure is at the very cold colour temperature of 6,800-7,200K, where the technology is likely to be emitting at its most efficient.

Exactly how efficient the material is not being revealed as the figures are pending publication in the journal Organic Electronics, said Carroll.

It is available on-line from the journal Organic Electronics.

He would say that operation is at "similar voltage to OLED", and that efficiency is "certainly comparable with compact fluorescents".

The university has described the technology as "at least twice as efficient as compact fluorescent bulbs and on par with LEDs".

Currently, high-end commercial LEDs are producing around 120lm/W, straight fluorescent tubes can approach 110 lm/W, and good compact fluorescents may approach 80 lm/W. Commercial OLEDs are extremely rare and lab figures would be un-representatively high.

The actual emissive layer is 200nm if a polymer called PVK, loaded with 10% of the light-emitting iridium compound Ir(ppy)3, and a fraction of a percent of nanotubes.

This is sandwiched between two 1.2µm layers of the ferroelectric polymer P(VDF–TrFE).

The nanotubes both inject electrons and generate charges, said Carroll, and the same structure without nanotubes produces only one fifth of the light.

The spectrum can be tuned to different colour temperatures.

"It is a continuous spectrum. We can almost make a perfect photopic curve," said Carroll.

Matching the eye's response - the photopic curve - would mean poor rendering of red and purple. Can he match the sun's spectrum instead?

"Yes, we can make the sun's spectrum," said Carroll.

The big problem for OLEDs is durability - water and oxygen from the atmosphere corrode the necessarily reactive electrodes and the organic materials involved.

There are no reactive metal electrodes in the FIPEL structure

"If a triplet hangs around, it will oxidise the material," said Carroll. "We have the shortest life of any triplets - so longer material life and much longer lifetime."

But how about moisture and oxygen?

"For our device to reach 20,000 hours, they still have to be encapsulated, but they are not so sensitive as OLEDs," said Carroll. "If you use expensive encapsulation, you will get 40,000-50,000 hours."

Wake Forest is working with a company to manufacture the technology and plans to have it ready for consumers in the next year.

Carroll sees potential uses in large display lighting in shops, busses and underground trains.

© Metropolis International Group Ltd.

http://www.electronicsweekly.com/Articles/04/12/2012/55131/fipel-more-on-the-oled-alternative-light-source.htm [with comments]


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Professor Invents The Best New Lightbulb In 30 Years


Wake Forest University physics professor David Carroll works with graduate student Greg Smith on new FIPEL lighting technology.
Wake Forrest University [ http://news.wfu.edu/2012/12/03/taking-the-buzz-out-of-office-lights/ ]

Dina Spector
Jan. 22, 2013, 3:22 PM

Lighting accounts for about 12 percent of total U.S. energy consumption [ http://www.eia.gov/tools/faqs/faq.cfm?id=99&t=3 ].

Part of the reason the figure is so high is that traditional incandescent bulbs (Edison's filament bulb) eat up a lot of power to produce light: 90 percent of the energy is wasted as heat.

So far the main alternatives to the common bulb have been compact fluorescent lights, or CFLs, and light-emitting diodes, or LEDs, which can produce the same amount of light as traditional bulbs while using way less energy.

Soon, a fourth lighting option will be thrown into the mix. It's called the FIPEL, which is short for field-induced polymer electroluminescent technology.

"This is the first new light bulb in about thirty years," says Dr. David Carroll, a professor of physics at Wake Forest University in North Carolina, who developed the new light source.

To understand how this technology functions, you can think of how a microwave works, Carroll explains.

Take a potato, for example. When you place your potato in the microwave and press start, the device hits the potato with microwaves that induce what's known as a displacement current, meaning it makes the water molecules in the potato flip back and forth. This heats the potato up. What Carroll and his team have done is develop a special type of plastic that, when hit with an electric current, induces a displacement current in the same way. But in this case, it doesn't give off heat, it gives off light.

The new light source is made of several layers of very thin plastic. Each sheet is about 100,000 times thinner than the width of a human hair. The plastic is inserted between an aluminum electrode and a transparent conducting electrode. When a current is passed through the device, it stimulates the plastic to light up.

Luckily for Carroll, FIPEL has entered the lighting technology ring at a time of unprecedented opportunity. The phaseout of traditional incandescent bulbs began to take effect at the start of the new year under the 2007 Energy Independence and Security Act.

As of Jan. 1, 2013, manufacturers can no longer sell 75-watt incandescents. The 40- and 60-watt incandescents will no longer be available starting Jan. 1, 2014.


FIPEL’s light quality is unmatched by any technology currently, the product's manufacturer claims.
Reprinted with permission of CeeLite Technologies [ http://www.ceelite.com/ ]

CFLs use about 75 percent less electricity than Edison's filament bulb to produce the same amount of light. LEDs use even less. This means to make the same light as a 100-watt incandescent, a compact fluorescent uses 23 watts and an LED uses 20.

The FIPEL is slightly more efficient than a CFL bulb and on par with an LED, but comes with a few advantages over these other types of lights. CFLs and other fluorescent light bulbs contain a very small amount of mercury, which can be toxic if not disposed of properly. FIPELs do not use any caustic chemicals in manufacturing and can easily be recycled because they're made of plastic.

Some LEDs give off a blueish tint, which many people don't like to look at. FIPEL, on the other hand, can be made to have any tint, including the yellowish hue of the sun that our eyes have come to prefer, having evolved on Earth.

"FIPEL can match the response of your eye more perfectly than any other lamp ever created," Carroll told Business Insider.

Although the new light source doesn't have the shape of a traditional light bulb — it's more a panel — it is moldable, so it can be customized to fit into conventional light sockets and work with many different types of lamp fixtures.

The FIPEL light has a lifetime of between 25,000 and 50,000 hours, which is comparable to an LED.

Carroll notes one drawback to FIPEL.

"From a pure physics point of view, the best efficiency that you could ever accomplish with this lamp is still going to be slightly lower than the best efficiency you could ever accomplish with an LED," says Carroll. Right now, LEDs do not perform at their theoretical best. But as both technologies mature, you can expect the LED to come out on top in terms of overall efficiency.

The FIPEL technology is currently under an exclusive world-wide license by CeeLite Technologies. David Sutton, management consultant for CeeLite, said the first units for commercial use will be available by the end of 2013. The new bulb will cost less than LEDs and slightly more than CFLs.

"In five years, instead of saying I've got to get a new bulb, you're going to be saying I've got to get a new FIPEL. I do believe that these are going to be ubiquitous," says Carroll.

Copyright © 2013 Business Insider, Inc.

http://www.businessinsider.com/fipel-lighting-technology-david-carroll-wake-forrest-2013-1 [with comments]